Control system for freezers

ABSTRACT

The present invention is directed to a freezing system of the hot gas type and a control system therefor. The freezing system is particularly directed to the type wherein a single motor is used to drive a dasher for a mix pump or pumps. The control system of the invention includes timing devices for controlling the start-up and shut-down of the freezing system in accordance with a predetermined sequence.

C United States Patent [151 3,667,244

Hock et al. 1 June 6, 1972 54] CONTROL SYSTEM FOR FREEZERS 3,059,44410/1962 Bickel et a1. ..62/1 35 [72] Inventors: nalter L. Hock, Skokie,1.; William E. Primary Examiner wmiam E Wayne,

Monroe Attorney-Anderson, Luedeka, Fitch, Even and Tabin [73] Assignee:Kraftco Corporation, New York, NY.

[57] ABSTRACT [22] Filed: Dec. 29, 1970 The present invention isdirected to a freezing system of the [21] APPLNO'Z 102,284 hot gas typeand a control system therefor. The freezing system is particularlydirected to the type wherein a single 52 US. Cl ..62/136, 62/233, 62/352motor is used to drive a flasher for a mix p p or p The 51 controlsystem of the invention includes timing devices for [58] Field of Search..62/136, 135, 233, 352 controlling the P and Shut-down of the freezingSystem in accordance with a predetermined sequence.

[56] References Cited 7 Claims, 2 Drawing Figures PATENTEDJUN 6 I972SHEET 10F 2 INVENTORS Maze .4. //0cx MLLMM Mrg5 A W i -IW, 6%,

ATTYS.

CONTROL SYSTEM FOR FREEZERS The present invention relates generally to afreezing device, such as an ice cream freezer, and more particularlyrelates to an improved control system for freezing devices wherein hotrefrigerant gas from the refrigerant system is automatically injectedinto the freezing device upon shut-down so as to instantly warm thecontents of the freezing chamber.

At the present time, many continuous ice cream freezers utilize theso-called hot gas refrigeration system in which hot refrigerant gas isautomatically injected into the evaporator of the freezing system uponshut-down to instantly warm the contents of the freezing chamber so asto substantially eliminate troublesome freeze-up of the freezingchamber. in hot gas refrigeration systems, hot refrigerant gas isinjected into the evaporator of the freezing system when the freezingsystem is shut down. The hot gas vaporizes the liquid refrigerantremaining in the evaporator. The vaporized refrigerant is then returnedto the compressor and condenser of the refrigerant system and isreturned to a liquid state. The use of hot gas permits remote startingand stopping of ice cream freezers by merely pushing a button.

A refrigeration system of the hot gas type is fully described in U.S.Pat. No. 3,059,444 to Fay D. Bickel et a]. However, the control systemsused to date for freezers using the hot gas principle have not beenentirely satisfactory. For those types of freezers using a common motordrive for the dasher and mix pump, there is a tendency to produce softand unusable ice cream when the freezing system is started after ashutdown.

Accordingly, it is a primary object of the present invention to providea control system for continuous ice cream freezers of the hot gas typethat will enable the freezing operation to be instantly started withoutthe production of soft ice cream. It is another object of the presentinvention to provide an improved continuous ice cream freezer of the hotgas type that will substantially reduce the amount of re-run uponstart-up. It is a further object of the present invention to provide acontinuous ice cream freezer of the hot gas type that has an improvedcontrol system and permits starting and stopping of the freezer bymerely pushing a button.

These and other objects of the invention will become more clear from thefollowing detailed description and the accompanying drawings, in which:

FIG. 1 is a diagrammatic presentation of a freezing system embodying thepresent invention; and

FIG. 2 is a diagram of a basic control circuit for the freezing systemof the invention.

Generally, the present invention is directed to a freen'ng system of thehot gas type and a control system therefor. The freezing system includesa condenser, a receiver, an expansion device, an evaporator, whichincludes a freezing tube for congealing a product supplied thereto, andan accumulator. All of the components of the freezing system areconnected in seriesflow relationship to form a refrigeration system. Thefreezing system also includes a dasher for agitating a product withinthe freezing tube and pumps for supplying a product to the freezingtube. The freezing system of the invention particularly is directed tothe type wherein a single motor is used to drive the dasher and a mixpump or pumps. The control system of the invention includes timingdevices for controlling the start-up and shut-down of the freezingsystem in accordance with a predetermined sequence.

More particularly, referring now to the drawings, as seen in FIG. 1, theprincipal components of the freezing system of the invention areillustrated. These components include a compressor 11, a condenser 13, areceiver 15, an accumulator l7 and an evaporator 19, all of theprincipal components being connected in series-flow relationship. Theevaporator 19 includes a freezing tube 21, into which an ice cream mixis introduced for freezing. Liquid refrigerant flows from the receiverthrough duct 23 to an automatically controlled expansion valve 25, whichmay be of any conventional type. Valve 27 is controlled by solenoid 29,and is used to shut off the flow of liquid refrigerant through duct 23as required.

The liquid refrigerant flows from the expansion valve 25 through duct31, which is connected at its other end to jet injector 33. The jetinjector 33 is located in accumulator 17 at a point below the liquidlevel that is maintained therein by float valve 35. Float valve 35controls the flow of refrigerant into the accumulator through a line 36connected with duct 23.

A duct 37 connected to the jet injector 33 carries the liquidrefrigerant into the evaporator 19, and a return line 39 carriesvaporized refrigerant from the evaporator 19 back to the accumulator 17from where it is withdrawn by compressor 11 through suction line 41. Thevaporized refrigerant is then compressed, condensed and again circulatedthrough the system.

A back pressure regulator valve 43 is located in line 41 to maintain thedesired pressure within the evaporator and thereby provide control ofthe freezing temperature. The regulator valve 43 variably restricts theamount of refrigerant gas flow in line 41 and thereby maintains thepressure in line 41 and the evaporator 19 at a desired value. Theregular 43 may be of any suitable type; however, regulator 43 ispreferably of a type that is controlled by a pilot valve 45 located in aline 46 which connects the control portion 47 of the regulator valve 43with line 41 at a point upstream from the regulator valve 43. When pilotvalve 45 is fully open, the control portion 47 of regulator valve 43senses the full pressure of line 41 and acts to fully open regulatorvalve 43 and permit full flow of refrigerant gas through line 41 fromevaporator 19, which results in maximum cooling of the refrigerationsystem. Pilot valve 45 is normally maintained in a partially opencondition so as to restrict the pressure to the control portion 47 ofregulator valve 43 and to thereby restrict and control flow ofrefrigerant gas through line 41 at less than maximum cooling. Regulatorvalve 43 may be fully closed by shutting off the flow of gas to thecontrol portion 47 of valve 43. The flow of gas to the control portion47 may be shut off by valve 48, which is controlled by solenoid 49;

Bypass line 50 is provided which routes the flow of refrigerant gasaround pilot valve 45 so as to remove the function of pilot valve 45 asa control on the regulator valve 43. When bypass line 50 is open, theflow of gas to the portion 47 of regulator valve 43 is sufficient tocause regulator valve 43 to remain in a fully open position. Bypass line50 is controlled by valve 51, which is actuated by solenoid 52.

Ice cream mix is supplied from a suitable source (not shown) and ispumped into the freezing tube 21 through a duct 53 by means ofmotor-driven mix pump 54. Air is incorporated into the mix to providethe desired amount of overrun through air line 55. The air is suckedinto pump 54 from the atmosphere through an adjustable air valve (notshown). The flow of air through air line 55 is further controlled byvalve 56, which is actuated by solenoid 57. Booster pump 58 may be usedto feed ice cream mix through line 61 at a positive pressure to mix pump54. A motor-driven dasher 59 constantly agitates the ice cream mix inthe freezing tube 21 to provide uniform freezing. Dasher 59 and mix pump54 are driven by a common motor 60.

Processed frozen ice cream is forced out of an outlet in the end offreezing tube 21 and into line 62. Throttle valve 63 regulates the flowof ice cream through line 62. Throttle valve 63 is air-controlled bycontroller 65. Controller 65 is actuated by pressure sensor 67 locatedin duct 53 which feeds ice cream mix from pump 54 to the freezing tube21. The operation of throttle valve 63 will be more fully describedhereinafter in connection with a discussion of the control system of theinvention. Check valve 69 is in duct 53 to prevent ice cream fromfreezing tube 21 from backing up in duct 53 to pump 54 when thefreezing-system is shut down.

The system as thus far described operates as follows: Liquid refrigerantis supplied from the high pressure side of compressor 11 to condenser 13and receiver 15. The liquid refrigerant is expanded and cooled byexpansion valve 25. The expansion valve 25 maintains the liquidrefrigerant at a suitable operating pressure for the jet injector 33.Liquid refrigerant in passing through injector 33 withdraws additionalrefrigerant from accumulator 17. Liquid refrigerant is then directedagainst the heat exchange surfaces of the freezing tube 21 to cool thecontents of the tube. As the refrigerant evaporates from the freezingtube 21, the vapor thus formed is returned through the duct 39 to theaccumulator 17 where gas and entrained liquid within the gas areseparated. The gaseous refrigerant is withdrawn from the accumulator 17through the suction line 41 to the compressor 1 1 for recirculationthrough the system. Regulator valve 43-maintains the desired pressureand temperature in the evaporator 19. The desired pressure andtemperature are set by manually adjusting pilot valve 45 which feeds agas pressure signal to the control portion 47 of regulator valve 43.

The freezing system is alsoprovided with meanswhereby hot gas may beautomatically injected into the evaporator 19 to warm the contents ofthe freezing tube 21 upon shutdown. in the hot gas portion of the freefreezing system, warm, vaporized refrigerant from the high pressure sideof compressor 11 is removed through a duct 71 that leads directly to theevaporator 19. The admission of the hot gas into the evaporator 19 iscontrolled by valve 73 which is actuated by solenoid 75. To warm thecontents of the freezing tube quickly, the pressure setting of theregulator valve 43 is changed to allow a higher than normal operatingpressure so as to build up the pressure of the hot gas in the evaporator19 rapidly. The pressure setting of regulator valve 43 is changed byproviding in duct 46 a valve 48 controlled by a solenoid 49 which shutsofi theflow of gas through the pilot valve 45 and allows a secondarypilot 77' to control regulator valve 43. The secondary pilot 77 is setso that the regulator valve 43 remains closed until valve 73 is closedto stop the admission of hot gas, or until apredetermined higherpressure of approximately 60 psig is reached. A pressure limit switch 79is provided to close the hot gas valve 73 when the pressure reaches apredetermined value of about 40 psig. The normal mode of operation ofthe hot gas valve in the control system of the present invention is suchthat the pressure limit switch 79 is not used to inactivate the hot gasvalve 73, as will be explained more fully hereinafter.

Referring now to FIG. 2, the electric control system of the presentinvention will be described in detail. The circuit is supplied from asource of electrical energy (not shown) which terminates in electricalsupply lines L1 and L2. The circuit includes an upper power circuit 80and a lower control circuit 81. A push button start switch 82 and a pushbutton stop switch 83 are connected across L1 and L2. The two switchesare used to start and stop the freezer system from a remote location bemeans of the control circuit 81. The control circuit 81 can beduplicated for each of several freezer systems so that each freezersystem can be remotely started and stopped by the switches 82 and 83.The two switches 82 and 83 are connected in series with a main holdingcoil 85 and a time delay holding coil 87. The main holding coil 85controls a set of main contacts 85a. When multiple freezer systems arebeing controlled, main holding coil controls a set of contacts in thecontrol circuit of each freezer system. For purposes of simplicity indescription only a single control circuit for a single freezer system isshown in FIG. 2. When the start button 82 is pressed, the main holdingcoil 85 is energized, closing the contacts 85a. This permits current toflow to holding coil 91. Holding coil 91 controls contacts 91a and 91b.When holding coil 91 is energized by closing the contacts 85a, holdingcoil 91 closes contacts 91a which act to lock holding coil 91 in anenergized condition. Main holding coil 85 also controls the contacts 85bwhich act to lock in the main holding coil 85 after the start switch ispressed..Current is supplied to lower control circuit 81 throughnormally closed contacts 131a, whose function is described hereinbelow.

Time delay holding coil 87 is of the type which is cocked when currentis applied and which is triggered when current is removed. When currentis removed from time delay holding coil 87, such as by pressing stopswitch 83, the time delay sequence is triggered. Time delay holding coil87 comes into use during the stop sequence, which is explained morefully below. Y

A bypass circuit around start switch 82 and stop switch 83 is provided.The bypass circuit includes an on-off switch 93, normally closedcontacts 850 and timer 95. Normally closed contacts c are controlled bymain holding coil 85. When the start switch is pressed, which activatesholding coil 85, the normally closed contacts 850 are opened. The on-offswitch 93 is then placed in the On" position. Subsequently, when thefreezer system is stopped and main holding coil 85 is deenergized, thenormally closed contacts 850 become closed and timer 95 is started. Thisprovides a-check on the elapsed time that the freezer is maintained in astop condition.

As previously indicated, energization of holding coil. 91

closes contacts 910 and 91b. This permits current to flow throughcontacts 91a and 9lb and energizes time delay holding coils 105, 107,109 and 1 11. Time delay holding coils 105, l07 and 109 are of the typewhich are cocked when no power is applied and which are triggered by theapplication of power. Time delay holding coil 111 is of the type whichis cocked by the application of power, and which is triggered upon thecessation of power.

Upon the application of power through contacts 85a, 91a and 91b, timedelay holding coil closes immediately and controls contacts 105a.Contacts 1050 are normally open and are closed when time delay holdingcoil 105 is activated. The contacts 105a are maintained closed for thetiming cycle of time delay holding coil 105. This time period is usuallymaintained at about 15 seconds, but may be adjusted within the range offrom about 5 to about 30 seconds. Closing of contacts 105a activatesholding coil 115. Holding coil 115 controls contacts 115a and 115b. Whenholding coil 115 is energized, contacts 115a and l15b are closed andpower is supplied to holding coil 133 and to solenoids 29 and 49, whichopen valves 27 and 48 respectively.

The closing of contacts 115a and 115!) also energizes holding coil 119.Holding coil 119 controls contacts 119a, 119b, 1l9c and 119d. Contacts 119a are used to lock in holding coil 119 when independent start switch121 and stop switch 123 are used. Independent stop and start switches121 and 123 are 4 located at individual freezers and are used to effectmanual operation of the system.

Contacts 1l9b are used to energize holding coil 125 when the timingsequence initiated by time delay holding coil 107'is terminated. Timedelay'holding coil 107, upon energization opens immediately and closesafter a time delay of from about 3 to about l5 seconds, preferably about5 seconds. Time delay holding coil 107 controls normally closed contacts107a. Dur ing the time period of time relay holding coil 107, contacts107a are open and holding coil 125 remains unenergized. After time delayholding coil 107 closes contacts 107a are closed and holding coil 125 isenergized. Holding coil 125 activates contacts 125a which, incombination with contacts 1 19c, lock in holding coil 125 to the circuitafter energization. Holding coil 125 also controls contacts 125b, whichlock in holding coil 1 19 to the circuit, and contacts 125C, which lockin solenoids 29 and 49, which hold valves 27 and 48 in the openposition. Holding coil 125 also closes contacts 125d, which completesthe circuit to solenoid 57 (which opens valve 56), pump 58 and motor 60.Thus, solenoid 57, pump 58 and motor 60 are not activated until afterthe time delay period introduced by time delay holding coil 107 hasterminated. Contacts 119d are used to open the circuit to solenoid 75when holding coil 119 is energized. Solenoid 75 controls valve 73 whichcontrols the flow of hot gas to the evaporator 19. Thus, hot gas is notadmitted to evaporator 19 when holding coil 119 is energized.

Time delay holding coil 109 opens immediately and closes after a periodof from about 5 to about 60 seconds, preferably about 15 seconds. Timedelay holding coil 109 controls contacts 109a. During the time periodinitiated by holding timing coil 109, contacts 109a are closed andsolenoid 52 is activated. Solenoid 52 opens valve 51 which permits afull pressure signal to be sent through bypass line 50 to the controlportion 47 of regulator valve 43. This holds regulator valve 43 in afully open position for the time period that time delay holding coil 109is set. This permits a maximum flow of refrigerant through the freezingsystem to effect maximum freezing during the timing period of time delayholding coil 109.

In summary of the control system to this point, after start switch 82 ispressed, main holding coil 85 is energized and power is supplied to timedelay holding coils 105, 107, 109 and 111. Timing coils 105, 107 and 109act to supply full refrigeration to freezing tube 21 for a time period.At the end of another time period, pump 58 and motor 60 are started.Motor 60 starts dasher 59 and mix pump 54. Solenoid 57 is activated andair is introduced through valve 56 and line 55. At the end of a furthertimed period, full refrigeration is stopped and normal controlledrefrigeration is supplied to freezing tube 21. The use of a controlledsequence for starting dasher 59, mix pump 54 and effecting fullrefrigeration for a controlled period acts to supply refrigerationsufficient to reduce the amount of soft ice cream that is producedduring start-up of the freezing system.

Throttling valve 63 is located at the output of freezing tube 21.Throttling valve 63 is controlled by a sensor which senses the pressurein mix line 53. The pressure in mix line 53 is controlled by theconsistency and hardness of the ice cream in freezing tube 21. When theconsistency and hardness of the ice cream in freezing tube 2l-are toolow, the pressure in mix line 53 drops and sensor 67 transmits a signalto controller 65 which sets throttling valve 63 so as to reduce theoutput of ice cream from freezing tube 21. This further reduces theamount of soft ice cream that is produced upon start-up of the freezingsystem.

When it is desired to stop the freezing system, stop switch 83 isdepressed. This interrupts current to main holding coil 85. When mainholding coil 85 is de-energized, contacts 850 are opened and holdingcoil 91 is de-energized. Time delay holding coil 87 is alsode-energized. This triggers the timing cycle of time delay holding coil87 which closes for a few seconds and then opens. Time delay holdingcoil 87 controls contacts 870, which close during the timing cycle.Closing of contacts 87a energizes holding coil 131. Holding coil 131controls normally closed contacts 131a and holds these contacts openduring the timing cycle of time delay holding coil 87. This interruptspower to the lower control circuit 81 by having contacts 131a and 85aopen simultaneously. After the timing cycle of time delay holding coil87 ends, contacts 131a are closed and power is again supplied to thelower control circuit 81 to permit manual operation and to operate thehot gas control sequence described hereinbelow.

interruption of power to the lower control circuit 81 drops out holdingcoils 125 and 115 and interrupts power to time delay holding coil 111.This stops motor 60, pump 58 and closes valves 56, 27, 48 and 51.

Upon interruption of current to time delay holding coil 111, the timingperiod is triggered and time delay holding coil 111 closes for a periodof from about three-fourths to about 5 minutes, preferably about 2minutes, and then opens. Time delay holding coil 111 controls normallyopen contacts 111a. Contacts 111a when closed during the timing cycle oftime delay holding coil 111 supply current to solenoid 75 which opensvalves 73 and permits hot gas to move into the freezing tube 21. Asindicated, the hot gas is permitted to flow into freezing tube 21 for atimed period which is controlled by time delay holding coil 111.Pressure switch 79 is present to permit closing valve 73 if the pressurewithin the freezing tube should rise to above about 40 psig.

For manual operation of the dasher and mix pump, which is desirableduring cleanup, switch 135 is closed so as to energize holding coil 125.When the switch 135 is closed, holding coil 125 is energized; contacts125a, 125b, 125C and 125d are then closed. Contact 125d supplies powerto and starts pump 58, motor 60, and energizes solenoid 57. Contacts125k and 125C have no effect since holding coil 91 is not energized andcontact 91b is open. The start system of the invention maybe manuallyinitiated and stopped by depressing start switch 121 or stop switch 123.When start switch 121 is depressed the timed relay sequences controlledby contact 91b are started.

Two-way switch 139 is used to supply power to solenoids 29 and 49 in itsdown position and to DPST momentary switch 141 in its up position.Switch 141 controls power to hot gas solenoid 75 or to solenoid 52.Power to hot gas solenoid 75 may be manually applied by depressingswitch 141 when switch 139 is in the up position. Power is appliedthrough normally closed contacts 119d and pressure limit switch 79. Whenswitch 141 is in its normal uppermost position, power is applied tosolenoid 52 which opens by pass valve 51. This power is applied throughnormally .closed contacts 111k and 133a. This permits a full flow ofrefrigerant gas to the control portion 47 of regulator valve 43 when therefrigeration system is oh. This maintains a maximum flow of refrigerantgas throughout the system during shut-down so as to keep the refrigerantin the accumulator as cold as possible during shutdown. This furtherreduces the amount of soft ice cream.

The freezing system of the present invention provides a control systemfor minimizing the amount of soft ice cream produced upon start-up of ahot gas freezing system which uses a common motor drive for the dasherand mix pump. The control system of the invention provides a unique timedelay actuation of the freezing system so as to effect minimization ofsoft ice cream.

What is claimed is:

l. A freezer apparatus comprising an evaporator, including a freezingtube to which the product to be frozen is supplied, first conduit meansfor conducting liquid product to said freezing tube, second conduitmeans for conducting frozen product away from said freezing tube, pumpmeans in said first conduit means for supplying product to said freezingtube, dasher means within said freezing tube for agitating said productduring cooling thereof, single motor means for driving both said dashermeans and said pump means, a first supply line to carry liquidrefrigerant to said freezing tube, a second supply line to carry hotrefrigerant gas to said freezing tube, a normally closed valve in sadsecond supply line, a refrigerant discharge line leading from saidfreezing tube to carry gaseous refrigerant therefrom, pressure regulatormeans in said refrigerant discharge line to control pressure atpreselected values, first timing means to inactivate said pressureregulator means for a first predetermined period and provide a maximumflow of liquid refrigerant to said freezing tube during said firstpredetermined period and second timing means for delaying activation ofsaid motor means for a second predetermined period occurring during atleast a portion of the time period of said first predetermined period.

2. A freezing apparatus in accordance with claim 1 wherein said firsttiming means and said second timing means are activated upon start-up ofthe freezing apparatus.

3. A freezing apparatus in accordance with claim 1 which furtherincludes third timing means for controlling the opening of said valve insaid second supply for a predetermined period.

4. A freezing apparatus in accordance with claim 3 wherein said thirdtiming means is activated upon shut-down of the freezing apparatus.

5. A freezing apparatus in accordance with claim 1 which furthercomprises throttle valve means in said second conduit means and pressuresensing means in said first conduit means, said pressure sensing meanscontrolling said throttle valve means at preselected values to controlthe softness of said frozen product.

6. An electrical control circuit for freezing apparatus having anevaporator including a freezing tube, a pump to supply liquid product tothe freezing tube, a dasher within the freezing tube to agitate theproduct while it is being frozen, a single motor for driving both thepump and the dasher, a pressure regulator for controlling the pressureof refrigerant supplied to the evaporator, an adjustable valve forcontrolling a pressure signal to the pressure regulator, a bypass linearound the adjustable valve, a first solenoid controlled .valve in thebypass line, a second solenoid controlled valve for controlling thesupply of refrigerant to the evaporator, and a third solenoid controlledvalve for controlling the supply of hot gas to the evaporator, saidcontrol circuit comprising an electrical power source, a stop switch, astart switch, a main holding coil c011 nected in series with said startand stop switches across said power source, first and second solenoidsfor said first and second solenoid controlled valves to open said valveswhen the respective solenoid is energized, a first time control relayand a second time control relay, said main holding coil being energizedwhen said start switch is pressed, said first and second time controlrelays being energized by said main holding coil, first and secondsolenoid being controlled by said first time control relay, said motorstarter circuit having a set of contacts operated by said second timecontrol relay, said first and second time control relays being set in away so that said first and second solenoids are opened a predeterminedperiod before said motor starter circuit is energized.

7. An electrical control circuit in accordance with claim 6 whichfurther comprises a third solenoid for controlling said third valve anda third time control relay, said third time control relay beingenergized when said stop button is pressed and said third time solenoidbeing controlled by said third time control relay so as to admit hot gasto the evaporator for predetermined period of time.

Patent No. 3,667 Dated June 6 1972 lnventofls) Walter L Hock & WilliamMyers I .It is certified that error appears in the. above-identifiedpatent .and that said LettersPaten't are hereby corrected as shownbelow:

Column 2, actual line 65, (indicated line 66) after "is" insertlocated-.

Column 3, line 17 delete "free" Column 4, actual line 47, (indicatedline 48) after v"3" insert -seconds.

Column 5, actual line 57 (indicated line 58) change "three-fourths" tol/4 minute.

' Column 6 actual line 44 (indicated line 4 5 after "control" insert--refrigerant (Claim 1) Signed and sealed this 2nd day of January 1973.

(SEAL) Attest:

EDWARD M.CFLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PC3-1050 USCOMM-DC 60376-P69 v 5.5. GOVERNMENT PRINTINGOFFICE l (939 O 356334

1. A freezer apparatus comprising an evaporator, including a freezingtube to which the product to be frozen is supplied, first conduit meansfor conducting liquid product to said freezing tube, second conduitmeans for conducting frozen product away from said freezing tube, pumpmeans in said first conduit means for supplying product to said freezingtube, dasher means within said freezing tube for agitating said productduring cooling thereof, single motor means for driving both said dashermeans and said pump means, a first supply line to carry liquidrefrigerant to said freezing tube, a second supply line to carry hotrefrigerant gas to said freezing tube, a normally closed valve in sadsecond supply line, a refrigerant discharge line leading from saidfreezing tube to carry gaseous refrigerant therefrom, pressure regulatormeans in said refrigerant discharge line to control pressure atpreselected values, first timing means to inactivate said pressureregulator means for a first predetermined period and provide a maximumflow of liquid refrigerant to said freezing tube during said firstpredetermined period and second timing means for delaying activation ofsaid motor means for a second predetermined period occurring during atleast a portion of the time period of said first predetermined period.2. A freezing apparatus in accordance with claim 1 wherein said firsttiming means and said second timing means are activated upon start-up ofthe freezing apparatus.
 3. A freezing apparatus in accordance with claim1 which further includes third timing means for controlling the openingof said valve in said second supply for a predetermined period.
 4. Afreezing apparatus in accordance with claim 3 wherein said third timingmeans is activated upon shut-down of the freezing apparatus.
 5. Afreezing apparatus in accordance with claim 1 which further comprisesthrottle valve means in said second conduit means and pressure sensingmeans in said first conduit means, said pressure sensing meanscontrolling said throttle valve means at preselected values to controlthe softness of said frozen product.
 6. An electrical control circuitfor freezing apparatus having an evaporator including a freezing tube, apump to supply liquid product to the freezing tube, a dasher within thefreezing tube to agitate the product while it is being frozen, a singlemotor for driving both the pump and the dasher, a pressure regulator forcontrolling the pressure of refrigerant supplied to the evaporator, anadjustable valve for controlling a pressure signal to the pressureregulator, a bypass line around the adjustable valve, a first solenoidcontrolled valve in the bypass line, a second solenoid controlled valvefor controlling the supply of refrigerant to the evaporator, and a thirdsolenoid controlled valve for controlling the supply of hot gas to theevaporator, said control circuit comprising an electrical power source,a stop switch, a start switch, a main holding coil connected in serieswith said start and stop switches across said power source, first andsecond solenoids for said first and second solenoid controlled valves toopen said valves when the respective solenoid is energized, a first timecontrol relay and a second time control relay, said main holding coilbeing energized when said start switch is pressed, said first and secondtime control relays being energized by said main holding Coil, first andsecond solenoid being controlled by said first time control relay, saidmotor starter circuit having a set of contacts operated by said secondtime control relay, said first and second time control relays being setin a way so that said first and second solenoids are opened apredetermined period before said motor starter circuit is energized. 7.An electrical control circuit in accordance with claim 6 which furthercomprises a third solenoid for controlling said third valve and a thirdtime control relay, said third time control relay being energized whensaid stop button is pressed and said third time solenoid beingcontrolled by said third time control relay so as to admit hot gas tothe evaporator for a predetermined period of time.